Castlet

What Castlet does

Castlet Ltd is a privately held UK engineering and manufacturing company, founded in 1974 and headquartered in Lincoln, England, operating as Castlet. It designs and produces bespoke industrial power and control systems across three core product lines: Electrostatic Precipitator (ESP) power and control solutions for industrial air pollution management; high-power industrial control and automation systems; and electro-mechanical and electronic design solutions for aerospace, marine, and defence applications. Supporting these products is a full lifecycle service suite covering commissioning, optimisation, calibration, remote/online services, spares and repairs, planned maintenance, 24/7 emergency callouts, and environmental chamber testing.

The company's business model combines project-based bespoke engineering engagements with recurring aftermarket service revenue. Pricing is quote-based and not publicly disclosed, reflecting the customized nature of each solution. Castlet sells to tier 1 enterprise clients, with BAE Systems named as a known defence customer, across three primary verticals: industrial energy and utilities (including waste-to-energy), manufacturing and industrial processing, and aerospace, marine, and defence. Its go-to-market combines direct enterprise field sales with a global partner/agent network, supported by content marketing, downloadable brochures, and a LinkedIn presence.

The underlying technology combines power electronics, transformer-rectifier design, industrial automation, and military-grade electronic engineering, with capabilities to refurbish and recalibrate legacy equipment, including 50-year-old assets. No data on revenue, ownership structure, certifications, or patents is disclosed; the firm is registered in England (Company No. 03729745) as a private limited company with 11-50 employees.

Name

Castlet

Legal name

Castlet Ltd

Website

https://castletltd.co.uk

Company type

Private

Founded year

1974

Operating status

Operating

Headcount range

11–50 employees

Short description

Castlet is a UK-based engineering and manufacturing firm, founded in 1974, that designs bespoke electrostatic precipitator power systems, high-power industrial control and automation, and aerospace/marine/defence electronic solutions for tier 1 enterprise clients worldwide.

Ownership category

akta.pro rank

Product category

Industrial Power and Control Systems Engineering

NAICS

Relay and Industrial Control Manufacturing (335314), Electrical Equipment Manufacturing (3353), Industrial and Commercial Fan and Blower and Air Purification Equipment Manufacturing (333413)

SIC

Electrical Industrial Apparatus (3620), Industrial & Commercial Fans & Blowers & Air Purifing Equip (3564), Electronic Coils, Transformers & Other Inductors (3677)

akta.pro primary industry

Industrial Control Cabinets & Power Distribution (Panels, Switchgear for Automation) (IMAHAHAK)

akta.pro secondary industry

Substation Control Houses, Enclosures & Physical Infrastructure (EUADACAK)

Keywords

• Electrostatic precipitator systems
• Industrial power control
• Automation systems engineering
• Aerospace defence electronics
• Air pollution management

Headquarters

HQ city

Lincoln

HQ country

United Kingdom

HQ region

Europe

Offices1 record

Markets served

GTM type

B2B

Offering type

Services

Cost components

Personnel, Operations, Technology or R&D, Supply Chain, Marketing or Sales

Revenue model

1. Engineering Solutions and Systems: Castlet provides comprehensive engineering services including consultancy, system design, software and hardware development, manufacturing, installation, and maintenance of ESP power systems, automation solutions, and defense electronics. Revenue is generated through project-based engagements and ongoing service contracts.
2. Spares, Repairs and Maintenance: Ongoing revenue from replacement parts, repair services, planned maintenance programs, and emergency callout services for existing installations.
3. Calibration Services: Precision calibration services for industrial control and power systems, including legacy equipment restoration.

Go-to-market motion1 record

Distribution channels2 records

Marketing channels3 records

Core offering

Castlet is an engineering and manufacturing company that designs, builds, and supports electrostatic precipitator (ESP) power and control systems for industrial air pollution control, along with power control and automation systems for industrial process plants. The company also delivers bespoke electronic and electromechanical solutions for the aerospace, marine, and defence sectors, operating as a full-lifecycle solution provider combining consultancy, system design, hardware and software development, manufacturing, installation, and ongoing maintenance services.

Product overview

Castlet offers a portfolio of three core product lines—ESP Power & Control (for industrial air pollution management), Power Control & Automation Systems (for high-power industrial automation), and Aerospace Marine & Defence Solutions (for military electronic design)—supplemented by a comprehensive suite of support services including commissioning, optimisation, calibration, remote/online services, spares & repairs, planned maintenance, emergency callouts, and environmental chamber testing. The company operates as a solution provider combining consultancy, system design, software & hardware development, manufacturing, installation, and maintenance services.

Differentiator

Problem solved

Functional benefit

Products and services

• ESP Power & Control Systems

Quantifiable outcome

• Extension of critical infrastructure life through refurbishment of transformer rectifiers in ESP power systems without downtime
• +1 more outcomes

Named customers1 record

Segments3 records

Ideal customer profiles3 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature4 records

Partnerships

One partnership is on record.

• Global PartnerscoreChannel Partner/ Reseller/ DistributorCastlet maintains a network of global partners who distribute and represent their engineering solutions in international markets. The partner program includes options for both global partnership and agent relationships.

Scale indicators3 records

Recent moves1 record

Expansion highlights4 records

Emerging players

• Trescal: Trescal is a specialist provider of calibration, metrology and asset-management services for industrial instrumentation. Comparable to Castlet's calibration and planned-maintenance services, especially for legacy power and control equipment.

Broad incumbents

• Siemens Energy: Siemens Energy provides large-scale power generation and transmission equipment including environmental control solutions for thermal power plants. Comparable on the high-power control and ESP-side, but operates as a global broad-line incumbent rather than a niche specialist.
• ABB: ABB is a broad incumbent in industrial automation, switchgear, power control and process electrification. Comparable to Castlet's Power, Control & Automation Systems line and to the high-power switchgear and control-panel aspects of its ESP business.
• GE Vernova: GE Vernova is a broad incumbent in power generation equipment, including emissions control systems and grid automation. Overlaps with Castlet on power-plant ESP systems and high-power control, but as part of a much wider portfolio rather than as a specialist.
• Rockwell Automation: Rockwell Automation is a global incumbent in industrial control, PLCs and automation systems. Comparable to Castlet's bespoke industrial automation and high-power control work, but addresses much broader process and discrete-manufacturing use cases.
• Andritz: Andritz supplies environmental and process technologies including emissions control, air-pollution control and industrial automation for power and pulp/paper sectors. Overlaps with Castlet's ESP, high-power control and industrial energy-and-utilities customer base as a global broad-line supplier.

Direct peers

• Ultra Electronics: Ultra Electronics provides specialised electronic and electro-mechanical systems for defence, aerospace and marine applications. Closely comparable to Castlet's Aerospace, Marine & Defence electro-mechanical and electronic design line, with similar Tier 1 prime-contractor customer profile.
• FLSmidth: FLSmidth supplies ESPs, fabric filters and gas cleaning equipment for cement, minerals and power industries. Comparable to Castlet on the air-pollution-control side and on bespoke high-power control systems for heavy industrial environments.
• Hamon: Hamon is one of the world's leading specialists in electrostatic precipitator (ESP) design, supply and refurbishment for power and industrial applications. Directly comparable to Castlet's ESP Power & Control line in terms of product, customer base (power plants, waste-to-energy, cement, steel) and aftermarket services.
• Babcock & Wilcox (B&W): B&W has a long heritage in electrostatic precipitator technology for power generation and industrial emissions control. Directly comparable to Castlet's ESP power and control offering and to its legacy equipment refurbishment capability.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat4 records

Key risks6 records

Key highlights6 records

Customer concentration

• LinkedInuk.linkedin.com/company/castlet-limited

Revenue estimate

Valuation estimate

Number of profiles

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Castlet